Oligonucleotides are useful in therapeutic, diagnostic, research and nanomaterials applications. The use of natural sequences of DNA or RNA for therapeutics is limited because of their instability against extra and intracellular nucleases, poor cell penetration and distribution. Additionally, in vitro studies have shown that the properties of antisense nucleotides such as binding affinity, sequence specific binding to the complementary RNA (Cosstick and Eckstein, 1985; LaPlanche et al., 1986; Latimer et al., 1989; Hacia et al., 1994; Mesmaeker et al., 1995), stability to nucleases are affected by the configurations of the phosphorous atoms Therefore, there is a need for modified oligonucleotides to impart stability towards ubiquitous nucleases, increase binding affinity towards complementary RNA and increase cell penetration and bio-distribution for a number of in-vitro and in-vivo applications.